Ventilated typewriter motor



1963 G. WGHLBIER ETAL 3,

VENTILATED TYPEWRITER MOTOR Filed March 31, 1960 2 Sheets-Sheet 1 Dec. 10, 1963 e. WC5HLBIER ETAL 3,113,658

VENTILATED TYPEWRITER MOTOR Filed March 31, 1960 2 Sheets-Sheet 2 United States Patent 3,113,658 VENTILATED TYPEWRITER MQTUR Gunther Wiihlhier, Grafschaft, uber Wilhelmshaven, and

Giinther Liider, Wilhelmshaven, Germany, assignors to Olympia Wei-he A.G., Wilhelmshaven, Germany Filed May 31, 1960, Ser. No. 32,998 Claims priority, application-Germany July 13, 1959 7 Claims. till. 197-16) The present invention relates to a ventilated typewriter motor, and more particularly to a blower arrangement for producing an axial air flow along the outer surface of a typewriter motor whose rotor is located on the outside of the stator.

The drive roll of an electric typewniter is preferably driven by a motor of the type having an outer rotor and an inner stator, since the greater radius of the outer rotor produces a comparatively great inertia as is desired for actuating the type actions.

Motors of this type tend to operate at comparatively high rotor temperatures. When the motor is arranged in the casing of a typewriter, in the region of the keyboard, the keys are heated to an extent which is not only detrimental for the typewriter, but also undesirable from the point of view of the operator.

To overcome this disadvantage of outer rotor motors, blowers and ventilating openings in the casing have been proposed. However, these solutions have not been fully successful, particularly since the space 'available for the motor in the typewriter casing is very small so that blowers cannot be provided with sufficiently great vanes without reducing the extent of the air gap between the rotary parts and the casing to an extent which would be unacceptable in view of the minimum distances required by the rules for electric apparatus.

It is one object of the present invention to provide a motor having an outer rotor and being constructed in such a manner that a typewriter mechanism driven thereby is not excessively heated.

Conventional blowers used for cooling motors produce a substantial airflow component extending in radial direction. Consequently, the heated air is discharged toward the casing of a typewriter and toward the keyboard, and is only slowly discharged from the casing of the typewriter.

It is therefore another object of the present invention to provide the drive motor of a typewriter with vane means producing an axial air flow along the rotor so that the heated air is conveyed away from the keyboard, and discharged at the end of the rotor where a possible heating of a casing portion will not be noticed by the operator.

With these objects in view, the present invention mainly relates to an electric motor located in the casing of an electric typing mechanism for effecting actuation of the type actions. The motor has an inner stator, and an outer rotor which has on the outer peripheral surface thereof helical vane means for creating in the casing of the typewriter mechanism a flow of air in axial direction of the rotor.

The pitch angle of the helical vane means should be rather steep, andthe vane means preferably extend along the entire axial length of the rotor.

The optimal pitch angle of the helical .vane means can be determined in accordance with the prevailing conditions depending on the rotary speed of the motor, and

.on the air volume which is to be conveyed. The helical vane means do not produce a radial component of the ,air flow, but obtain an axial stream of air by which practically all developed heat is conveyed out of the casing of the typewriter.

A minimum distance must be maintained between the ice metal parts of an electric apparatus, and in order to obtain the smallest possible gap between the vanes and the casing or other metal parts of the typewriter, the vanes are preferably made of an artificial synthetic insulating material.

In one embodiment of thepresent invention, the ventilating means include a pair of holding rings, and elongated iiexibie vanes extending between the holding rings. The holding rings are attached to the outer rotor of the drive motor, and are turned relative to each other until the elongated flexible vanes assume a helical shape whose pitch angle can be'de-termined by turning the holding rings to a selected angularly displaced position. In this position, the holding rings are attached to the ends of the rotor, with the now helical vanes extending-along the peripheral outer surface of the rotor. A preferred attachment of the holding nings is carried out by shrinking of the holding rings onto the rotor.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of openation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in. which:

FIG. 1 is a fragmentary perspective view illustrating a part of a typewriter mechanism in which the arrangement of the present invention is advantageously used:

FIG. 2 is a fragmentary schematic cross-sectional View showing the motor and a portion of the typewriter casing;

and

FIG. 3 is a schematic side View illustrating a ventilating attachment according to one embodiment of the present invention.

Referring now to the drawings, and more particularly to FIG. 1, a motor 1 is mounted in the forward portion of a typewritercasing 2 and has an outer rotor 11, and an inner stator 12, shown in FIG. 2. A plurality of helical vanes 13 is secured to the outer peripheral surface 14 of rotor H. The vanes extend parallel to each other and form a multiple helix having its axis coinciding with the axis of rotation .of rotor 11. In the typewriter construction shown in FIG. 1, the space bar 21 is located in the region of the motor, and in the embodiment of FIG. 2, a type key lever 22 is located directly above motor 1. When the respective key lever is depressed, a certain minimum distance must be maintained between the key lever and the metal parts of the motor. "In accordance with a preferred embodiment of the pres ent invention, the helical vanes 13 are made of an insulating artificial material, so that the minimum distance need not be maintained between the vanes and the key levels, but between the .outer peripheral surface 14 of the rotor and the key levers. In this manner, a maximum diameter and corresponding great inertia can be achieved for a motor which is to .be built into a casing 2 having predetermined dimensions. The minimum insulating air gap must be maintained between the .key levers in depressed position, and the respective adjacent metal portion of the rotor.

The helical vanes 13 of the present invention can be inserted into cor-responding grooves on the peripheral surface 14 of the rotor, or may be soldered, welded, adhesively attached, or secured by other attaching means.

In the preferred embodiment of the present invention, a ventilating attachment is provided for motor 1, which may be independently manufactured. The yentilating arrangement is shown in FIG. 3 and includes two .holdin g rings 3, and a plurality, for example four, flexible elongated'vanes 13a which are advantageously elongated bars having rectangular cross-sections, and tending to assume a straight position. Holding rings 3 have inner circular surfaces matching the cylindrical peripheral surface 14 of the rotor and having the same diameter. The ventilating attachment is placed about rotor 11, and rings 3 are turned relative to each other until the flexible vanes 13a assume helical shape and form a multiple helix. The holding rings 3 are then attached to rotor 11, so that the flexible vanes 13a are rigidly held, and cannot turn to their original straight position. In this manner, it is possible to determine the pitch angle of the helix during the mounting of the ventilating attachment and to choose the pitch angle in accordance with the prevailing conditions.

In one embodiment of the ventilating attachment shown in FIG. 3, holding rings 3 are heated before being placed on the rotor 11, and then permitted to cool so as to shrink to a reduced diameter in which they engage the peripheral surface 14 of the rotor under pressure, which will be sufficient to hold the vanes 13a in helical shape.

Shaft 15 of rotor 11 carries a pulley 16 which drives a pulley 16a through a belt 16b. Pulley Ida is shown spaced from the power roll 17 in the partly exploded view of FIG. 1, but is normally seated on the square portion 17a to drive the drive roll 17. When the lever arm of an angular lever 18 is engaged by the respective key, the other arm of lever 18 is turned to a position in which drive roll 17 actuates the type lever action 19.

Motor 1 rotates continuously and drives drive roll 17. During rotation of rotor 11, the helical vanes 13 produce an axial how of air along the rotor so that the hot air does not reach the top of the casing 2, or the type levers.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of ventilated motors differing from the types described above.

While the invention has been illustrated and described as embodied in a ventilating attachment for a typewriter motor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An electric motor comprising an inner stator and a outer rotor; a plurality of flexible vanes located on the outer peripheral surface of said rotor and extending along the length thereof; and a pair of holding rings secured to the ends of said flexible vanes and being turnable relative to each other about the axis of said rotor, said holding rings having inner surfaces abutting the outer peripheral surface of said rotor and being attached to the ends of said rotor in a relative angular position in which said flexible vanes have the shape of a multiple helix having a selected pitch angle.

2. A ventilating arrangement comprising, in combination, a motor including an elongated rotor having an axis of rotation; elongation flexible resilient vane means having a normal straight position and extending in longitudinal direction of said rotor projecting a radical direction from the peripheral surface of the same; a pair of holding means secured to the ends of said vane means and mounted at the ends of said rotor for turning movement relative to each other and to said rotor to a selected relative angular position in which said ends of said vane means are angularly turned relative to each other; means for securing each holding means independently of the other holding means to said rotor in said selected angular position so that said holding means rigidly hold said vane means in said angular position whereby said vane means is resiliently twisted and deformed and has a helical shape for creating an axial flow of air along said rotor.

3. A ventilating arrangement comprising, in combination, a motor including an elongated rotor having an axis of rotation; a plurality of elongated flexible resilient vanes having a normal straight position and extending in longitudinal direction of said rotor projecting in radial direction from the peripheral surface of the same, said vanes having edges at the ends thereof radially projecting from said peripheral surface; a pair of holding rings having confronting inner faces secured to said edges of said vanes, said rings being mounted at the ends of said rotor for turning movement relative to each other and to said rotor to a selected relative angular position in which said ends of said vanes are angularly turned relative to each other; means for securing by shrinking each holding ring independently of the other holding ring to said rotor in said selected angular position so that said holding rings rigidly hold said vanes in said angular position whereby said vanes are resiliently twisted and deformed and have a helical shape for creating an axial how of air along said rotor.

4. In an electric typing mechanism including type lever actions, a drive roll for actuating said type lever actions, and a keyboard including a plurality of keys respectively associated with said type lever actions, in combination, a casing; an electric motor located in said casing and having an inner stator and an elongated outer rotor connected with said drive roll for rotating the same for actuation of said type lever actions, said rotor having a horizontal axis of rotation and being located below said keyboard, said rotor having on the outer peripheral surface thereof elongated vane means extending along the length thereof for creating a flow of air in axial direction of said rotor along said outer peripheral surface thereof whereby air heated by said motor cannot rise toward said casing and said keyboard.

5. In an electric typing mechanism including type lever actions, a drive roll for actuating said type lever actions, and a keyboard including a plurality of keys respectively associated with said type lever actions, in combination, a casing; an electric motor located in said casing and having an inner stator and an elongated outer rotor connected with said drive roll for rotating the same for effecting actuation of said type lever actions, said rotor having a horizontal axis of rotation and being located below said keyboard, said rotor having on the outer peripheral surface thereof a plurality of elongated helical vanes forming a multiple helix having an axis coinciding with the axis of said rotor and extending along the length thereof for creating a flow of air in axial direction of said rotor along said outer peripheral surface thereof whereby air heated by said motor cannot rise toward said casing and said keyboard.

6. A typing mechanism as set forth in claim 5 wherein said vanes consist of an insulating material, and wherein at least said casing consists of metal and is closely spaced from said vanes so that said peripheral surface of said rotor is separated by said insulating vanes from said metal casing portion of said casing.

7. In an electric typing mechanism including type lever actions, a drive roll for actuating said type lever actions, and a keyboard including a plurality of keys respectively associated with said type lever actions, in combination, a casing; an electric motor located in said casing and having an inner stator and an elongated outer rotor connected with said drive roll for rotating the same for effecting actuation of said type lever actions, said rotor having a horizontal axis of rotation and being located below said keyboard; a plurality of flexible vanes located on the outer peripheral surface of said rotor extending along the length thereof; and a pair of holding members secured to the ends of said flexible vanes and to the ends of said rotor and being turnable relative to each other about the axis of said rotor, said holding members being attached to said ends of said rotor in a selected relative angular position in Which said flexible vanes have the shape of a multiple helix having a selected pitch angle so that said varies create a flow of air in axial direction of said rotor along said outer peripheral surface thereof whereby aid heated by said motor cannot rise toward said casing and said keyboard.

References (Iited in the file of this patent UNITED STATES PATENTS Re. 25,024 Barkdoll Aug. 15, 1961 1,075,120 Rodgers Oct. 7, 1913 1,165,931 Akimoff Dec. 28, 1915 1,632,357 White June 14, 1927 2,256,659 Thrasher Sept. 23, 1941 2,315,235 Weidner et a1 Mar. 30, 1943 

4. IN AN ELECTRIC TYPING MECHANISM INCLUDING TYPE LEVER ACTIONS, A DRIVE ROLL FOR ACTUATING SAID TYPE LEVER ACTIONS, AND A KEYBOARD INCLUDING A PLURALITY OF KEYS RESPECTIVELY ASSOCIATED WITH SAID TYPE LEVER ACTIONS, IN COMBINATION, A CASING; AN ELECTRIC MOTOR LOCATED IN SAID CASING AND HAVING AN INNER STATOR AND AN ELONGATED OUTER ROTOR CONNECTED WITH SAID DRIVE ROLL FOR ROTATING THE SAME FOR ACTUATION OF SAID TYPE LEVER ACTIONS, SAID ROTOR HAVING A HORIZONTAL AXIS OF ROTATION AND BEING LOCATED BELOW SAID KEYBOARD, SAID ROTOR HAVING ON THE OUTER PERIPHERAL SURFACE THEREOF ELONGATED VANE MEANS EXTENDING ALONG THE LENGTH THEREOF FOR CREATING A FLOW OF AIR IN AXIAL DIRECTION OF SAID ROTOR ALONG SAID OUTER PERIPHERAL SURFACE THEREOF WHEREBY AIR HEATED BY SAID MOTOR CANNOT RISE TOWARD SAID CASING AND SAID KEYBOARD. 